• Title, Summary, Keyword: Cache replacement

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Cache Optimization on Hot-Point Proxy Caching Using Weighted-Rank Cache Replacement Policy

  • Ponnusamy, S.P.;Karthikeyan, E.
    • ETRI Journal
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    • v.35 no.4
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    • pp.687-696
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    • 2013
  • The development of proxy caching is essential in the area of video-on-demand (VoD) to meet users' expectations. VoD requires high bandwidth and creates high traffic due to the nature of media. Many researchers have developed proxy caching models to reduce bandwidth consumption and traffic. Proxy caching keeps part of a media object to meet the viewing expectations of users without delay and provides interactive playback. If the caching is done continuously, the entire cache space will be exhausted at one stage. Hence, the proxy server must apply cache replacement policies to replace existing objects and allocate the cache space for the incoming objects. Researchers have developed many cache replacement policies by considering several parameters, such as recency, access frequency, cost of retrieval, and size of the object. In this paper, the Weighted-Rank Cache replacement Policy (WRCP) is proposed. This policy uses such parameters as access frequency, aging, and mean access gap ratio and such functions as size and cost of retrieval. The WRCP applies our previously developed proxy caching model, Hot-Point Proxy, at four levels of replacement, depending on the cache requirement. Simulation results show that the WRCP outperforms our earlier model, the Dual Cache Replacement Policy.

Document Replacement Policy by Site Popularity in Web Cache (웹 캐시에서 사이트의 인기도에 의한 도큐먼트 교체정책)

  • Yoo, Hang-Suk;Jang, Tea-Mu
    • Journal of Korea Game Society
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    • v.3 no.1
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    • pp.67-73
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    • 2003
  • Most web caches save documents temporarily into themselves on the basis of those documents. And when a corresponding document exists within the cache on wei s request, web cache sends the document to corresponding user. On the contrary, when there is not any document within the cache, web cache requests a new document to the related server to copy the document into the cache and then rum it back to user. Here, web cache uses a replacement policy to change existing document into a new one due to exceeded capacity of cache. Typical replacement policy includes document-based LRU or LFU technique and other various replacement policies are used to replace the documents within cache effectively. However, these replacement policies function only with regard to the time and frequency of document request, not considering the popularity of each web site. Based on replacement policies with regard to documents on frequent requests and the popularity of each web site, this paper aims to present the document replacement policies with regard to the popularity of each web site, which are suitable for latest network environments to enhance the hit-ratio of cache and efficiently manage the contents of cache by effectively replacing documents on intermittent requests by new ones.

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Document Replacement Policy by Web Site Popularity (웹 사이트의 인기도에 의한 도큐먼트 교체정책)

  • Yoo, Hang-Suk;Chang, Tae-Mu
    • Journal of the Korea Society of Computer and Information
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    • v.13 no.1
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    • pp.227-232
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    • 2008
  • General web caches save documents temporarily into themselves on the basis of those documents. And when a corresponding document exists within the cache on user's request. web cache sends the document to corresponding user. On the contrary. when there is not any document within the cache, web cache requests a new document to the related server to copy the document into the cache and then turn it back to user. Here, web cache uses a replacement policy to change existing document into a new one due to exceeded capacity of cache. Typical replacement policy includes document-based LRU or LFU technique and other various replacement policies are used to replace the documents within cache effectively. However. these replacement policies function only with regard to the time and frequency of document request. not considering the popularity of each web site. Based on replacement policies with regard to documents on frequent requests and the popularity of each web site, this paper aims to present the document replacement policies with regard to the popularity of each web site, which are suitable for latest network environments to enhance the hit-ratio of cache and efficiently manage the contents of cache by effectively replacing documents on intermittent requests by new ones.

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Remote Cache Replacement Policy using Processor Locality in Multi-Processor System (다중 프로세서 시스템에서 프로세서 지역성을 이용한 원격 캐쉬 교체 정책)

  • Han Sang Yoon;Kwak Jong Wook;Jhang Seong Tae;Jhon Chu Shik
    • Journal of KIISE:Computer Systems and Theory
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    • v.32 no.11_12
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    • pp.541-556
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    • 2005
  • The memory access latency of the system has been a primary factor of performance degradation in single-processor system and multi-processor system. The remote memory access latency takes a lot of overhead over the local memory access latency especially in the distributed shared-memory system. To resolve this problem, the multi-level cache architecture that contains a remote cache in the multi-processor system has been proposed. In this paper, we propose a new cache replacement policy that improves the performance of the multi-processor system with the remote cache. If the multi-level cache keeps the multi-level inclusion(MLI) property and uses the LRU(Least Recently Used) cache replacement policy, the LRU information of the higher-level cache(a processor cache) would be different with that of the lower-level cache(a remote cache). In this situation, the replacement of a remote cache line can induce the exchange of a processor cache line that is used by the processor. It is a main factor of performance degradation in a whole system. To alleviate this disadvantage of the LRU replacement polity, the new policy analyses tht processor's remote memory access pattern of each node and uses this information to reduce the number of invalidations of the useful cache line in the higher-level cache. The new replacement policy of the remote cache can improve the performance by $3.5\%$ in maximum and $2.5\%$ in average on SPLASH-2 benchmarks, compared to the general LRU cache replacement policy.

Shelf-Life Time Based Cache Replacement Policy Suitable for Web Environment (웹 환경에 적합한 보관수명 기반 캐시 교체정책)

  • Han, Sungmin;Park, Heungsoon;Kwon, Taewook
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.40 no.6
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    • pp.1091-1101
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    • 2015
  • Cache mechanism, which has been a research subject for a significant period of time in computer science, has become realized in the form of web caching in network practice. Web caching has various advantages, such as saving of network resources and response time reduction, depends its performance on cache replacement policy, therefore, analysis and consideration of the environment in which a web cache operates is essential for designing better replacement policies. Thus, in the current web environment where is rapidly changing relative to the past, a new cache replacement policy is necessary to reflect those changes. In this paper we stipulate some characteristics of the web at present, propose a new cache replacement policy, and evaluate it.

Dynamic Cache Partitioning Strategy for Efficient Buffer Cache Management (효율적인 버퍼 캐시 관리를 위한 동적 캐시 분할 블록교체 기법)

  • 진재선;허의남;추현승
    • Journal of the Korea Society for Simulation
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    • v.12 no.2
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    • pp.35-44
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    • 2003
  • The effectiveness of buffer cache replacement algorithms is critical to the performance of I/O systems. In this paper, we propose the degree of inter-reference gap (DIG) based block replacement scheme that retains merits of the least recently used (LRU) such as simple implementation and good cache hit ratio (CHR) for general patterns of references, and improves CHR further. In the proposed scheme, cache blocks with low DIGs are distinguished from blocks with high DIGs and the replacement block is selected among high DIGs blocks as done in the low inter-reference recency set (LIRS) scheme. Thus, by having the effect of the partitioning the cache memory dynamically based on DIGs, CHR is improved. Trace-driven simulation is employed to verified the superiority of the DIG based scheme and shows that the performance improves up to about 175% compared to the LRU scheme and 3% compared to the LIRS scheme for the same traces.

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Efficient Document Replacement Policy by Web Site Popularity

  • Han, Jun-Tak
    • International Journal of Contents
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    • v.3 no.1
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    • pp.14-18
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    • 2007
  • General replacement policy includes document-based LRU or LFU technique and other various replacement policies are used to replace the documents within cache effectively. But, these replacement policies function only with regard to the time and frequency of document request, not considering the popularity of each web site. In this paper, we present the document replacement policies with regard to the popularity of each web site, which are suitable for modern network environments to enhance the hit-ratio and efficiently manage the contents of cache by effectively replacing documents on intermittent requests by new ones.

Replacement Algorithm Selection Mechanism Considering File Size for Web Cache Server

  • Sontisiri, Tanasun;Sopechoke, Pawin;Thipchaksurat, Sakchai;Varakulsiripunth, Ruttikorn
    • 제어로봇시스템학회:학술대회논문집
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    • pp.1084-1089
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    • 2004
  • This paper describes the improvement of web cache server by scoping in replacement algorithm of data which are collected from the clients. We have found that each replacement algorithm is suitable for each type of data in the web pages. Therefore, we introduce the mechanism to select the replacement algorithm depending on the size of data called the Replacement Algorithm Selection Mechanism (RASM). RASM allows the web cache server to have the suitable replacement algorithm for each type of data. As the result, the byte hit ratio of web cache server can be increased and the congestion in the network can be alleviated.

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SBR-k(Sized-base replacement-k) : File Replacement in Data Grid Environments (SBR-k(Sized-based replacement-k) : 데이터 그리드 환경에서 파일 교체)

  • Park, Hong-Jin
    • The Journal of the Korea Contents Association
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    • v.8 no.11
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    • pp.57-64
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    • 2008
  • The data grid computing provides geographically distributed storage resources to solve computational problems with large-scale data. Unlike cache replacement policies in virtual memory or web-caching replacement, an optimal file replacement policy for data grids is the one of the important problems by the fact that file size is very large. The traditional file replacement policies such as LRU(Least Recently Used), LCB-K(Least Cost Beneficial based on K), EBR(Economic-based cache replacement), LVCT(Least Value-based on Caching Time) have the problem that they have to predict requests or need additional resources to file replacement. To solve theses problems, this paper propose SBR-k(Sized-based replacement-k) that replaces files based on file size. The proposed policy considers file size to reduce the number of files corresponding to a requested file rather than forecasting the uncertain future for replacement. The results of the simulation show that hit ratio was similar when the cache size was small, but the proposed policy was superior to traditional policies when the cache size was large.

Preventing Fast Wear-out of Flash Cache with An Admission Control Policy

  • Lee, Eunji;Bahn, Hyokyung
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.15 no.5
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    • pp.546-553
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    • 2015
  • Recently, flash cache is widely adopted as the performance accelerator of legacy storage systems. Unlike other cache media, flash cache should be carefully managed as it has peculiar characteristics such as long write latency and limited P/E cycles. In particular, we make two prominent observations that can be utilized in managing flash cache. First, a serious worn-out problem happens when the working-set of a system is beyond the capacity of flash cache due to excessively frequent cache replacement. Second, more than 50% of data has no hit in flash cache as it is a second level cache. Based on these observations, we propose a cache admission control policy that does not cache data when it is first accessed, and inserts it into the cache only after its second access occurs within a certain time window. This allows the filtering of data disruptive to flash cache in terms of endurance and performance. With this policy, we prolong the lifetime of flash cache 2.3 times without any performance degradations.